To verify Virginia license issued by the Virginia Department of Professional and Occupational Regulation use this online service. You will be able to see the license status, complaint history, and more.
You can also check if there were any disciplinary actions against Virginia contractor, plumber, or other tradesman using this online search.

To complain about Virginia contractor, plumber, or other tradesman download this complaint form. You can also find complaint form, instructions, and learn more about Virginia contractor complaint process here.

Virginia Board for Contractors has the Contractor Transaction Recovery Fund that may compensate you for up to $20,000 of your actual monetary loss through the improper or dishonest conduct of a licensed contractor. (A court judgment against contractor is needed).

You can complain about plumber or contractor to the Consumer Protection section of the Office of the Attorney General of Virginia online or download a consumer complaint form, fill it out and mail to:
Office of the Attorney General of Virginia
Consumer Protection Section
900 East Main Street
Richmond, VA 23219
Fax: (804) 225-4378

Go to http://www.bbb.org/ and enter your zip code. When your local BBB page appear click on the "FILE A COMPLAINT" link and follow directions.

4. Virginia Small Claims: (For your information only - not a legal advice)

You can file your Virginia small claims suit in the county where your contractor lives, or does business, or where he performed the service for you.To start small claims lawsuit in Virginia file your civil Warrant in Debt form with a clerk of the small claims division of the general district court. You can find a Warrant in Debt form for download here or directly download it online.
At the time of filing you will have to pay a filing and service fees (may vary).
You can find location and links to your local Virginia district court here.

5. On-line complaints.

We collect all sorts of customer reviews, complaints, and comments here.
To post your comment on Google find your contractor in Google maps, and click the more info link next to the name of your contractor. On the following page, scroll down to Reviews by Google users and click on Rate and review link on the left.
There are many other websites that let you post comments and complaints about your contractor. Below you may find just a few examples:
1) http://www.ripoffreport.com (registration required),
2) http://www.complaintsboard.com/
3) www.complaints.com